Oil burner



June I 'w. o. BEHRENS I 2 on. BURNER I Filed June 25, 1937 Patented June4, 1940 UNITED STATES PATENT OFFICE OIL BURNER William -0. Behrens,Harvey, Ill. Application June25, 1937, Serial No. 150,279

7 Claims.-

The invention relates to oil burners and more particularly to the typeof oil or liquid fuel burner in which all of the air necessary forcombustion, both primary and secondary, is supplied by forced draft tothe primary and secondary .air. nozzles.

The present application is a continuation in" Parent in the followingdescription taken in connection .with the accompanying drawing, inwhich:

Figure 1 is a'longitudinal sectional view of an oil burner embodying thefeatures of the invention.-

-Fig. 2 is an end view in elevationof a rotary blower with a section ofthe blower broken away to show the underlying construction.

- Fig. 3 is a transverse sectional view taken substantially along line3-3 of Fig. 1.

While the inventionis susceptible of various modifications andalternative constructions, I have shown in the drawing'and will hereindescribe indetail, thepreferred embodiment, but it is to be understoodthat I do not thereby intend to limit the invention to the specific formdisclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit the plate I! to hold the nozzlesin The oil burnershown in the drawing for purposes of disclosure is ofthe type adapted todls-' charge a turbulent mixture of atomized fuel andair conditioned for, efllcient combustion, preferably into a sealedfurnace. The present invention is embodied in a burner having a primaryair nozzle l coaxially alined witha circumand coacts therewith thoroughmixing of is supplied to the primary nozzle by means of a compoundrotaryblower (indicated generally at H) enclosed within a housing iii.The housing is together with -a cover I9 is suitably supported to formthe outer wall of an air passage opening to the nozzle H and to thesource of secondary air supply. The cover is is formed with a suitablyapertured plate member 2i extending transversely of the sure low volumeair axis and terminating in an inner ring 22 to pro- 1 v A rotary dampermember 23,

' apertured, is operatively disposed against the plate member 2i and isadjustable by means of 15 a rod 25 pivotally connected to one sidethereof and extending out of the housing. a The primary air nozzle ismounted on the en of a tube 28 which constitutes the outlet from:

the source of primary high pressure am- .The

tube 26 is supported on the ring 22 in spaced relation to the coverplate iii to provide an inner wall for the secondary air passage 20. Thesecondary air nozzle i i, having substan tially the shape of a Venturitube, comprises, in 26 the present instance, an inlet cone, anintermediate straight throat and an expanding outlet cone. The primaryair nozzle ill extends substantially through the secondary air nozzle Hondary air passage. The primary airnozzle is tapered toward itsdischarge end within the outlet cone of the secondary air nozzle toexpand the outer endof the secondary air passage. An atomizing cup 41,mounted for rotation, as hereinafter described, extends coaxiallysubstantially through the primary nozzle i0 and coacts therewith todefine an annular primary air passage restricted in the region oftaperof said primary air nozzle. 40 Thus it will be apparent that the primaryand secondary air nozzles coact to define an -in= tervening annularair'passage for the secondary air having substantially a Venturi shapein cross section taken longitudinally of said passage, resulting inan'increased turbulence, of the air discharged at the nozzle and,consequently, more the fuel and air and more effective combustion.Likewise the opposed walls of the atomizing cup and the primary airnozzle being relatively inclined to each other progressive- Y lyrestrict the flow area of the outer end portion of the-primary a rpassage to increase the speed of discharge of the primary air for moreeflicient combustion. is

to define an annular sec- 1 fuel supply tube 49.

The blower construction 11 supplies both primary and secondary air tothe nozzles from a unitary compound In the present instance, the bloweris mounted for'rotation on a horizontally disposed drive shaft 21 andhas the form of a double disk fan with an axial inlet 28 graduallyenlarging radially to communicate with a radially extending annular airpassage 23 having a peripheral discharge 29 for high pressure air and anannular inlet 30 circumscribing the axial inlet 28 and-communicatingwith a peripheral 3| for low pressure air. Since the air pressuredelivered by a disk fan is a function of the tip speed of the blades,the diameter of the peripheral discharge 29 for high pressure air isgreater than that for low pressure air and I employ fan blades(illustrated at 32) of considerably length in the former than the blades(indicated at 33) in the latter. Likewise the blades in the low pressureside are broader than those on the high pressure side since a greatervolume of air is desired in the former. Peripherally disposedsupplementary blades 32 may be provided for the high pressure stage asauxiliary air impellers.

An internal housing 34 encloses the high pressure side of the fan andtogether with a circular baflle or guide plate 35 serves to direct airfrom the primary discharge inwardly to the tube 26. The housing 34 hasan inner end wall 36 which together with the housing l8 forms an airpassage 31 between the low pressure discharge and the passage 20 to thesecondary air nozzle. The low pressure side'of the blower, althoughsmaller in diameter discharges substantially parallel thereto into thehousing l8 and the secondary air is directed into the passage 31 betweensaid housings and hence into the passage 20 to the secondary nozzle.

To promote an intimate fuel mixture and flne atomization of the fuel,two sets of peripherally spaced helical vanes 38 and 39 are disposed respectively within the nozzles Hi and II in the high pressure and lowpressure air discharge passages. These sets of vanes are oppositelyinclined and rigid with respect to the nozzles. Nozzles with vanes ofdifferent inclination may be substituted depending on the nature of theflame desired. Thus, the flame may be long and narrow or short and wide.The vanes are so orientated that, assuming the atomizing cup 41 isrotating clockwise when viewed from the left in Fig. l, the highpressure primary air is discharged counterclockwise, and the lowpressure secondary air is discharged clockwise.

Enclosing the inlet side of the housing a cylindrical housing having aplurality of air inlets 4| opening from the atmosphere. The inner endwall of the housing 40 is formed with an axial outlet opening 42communicating wi the blower intakes 28 and 30, and which is in directregistration and closely interfltting relation therewith.

The shaft 21 extends into the housing 40 where it may be suitablyjournaled in spaced bearings 44 and driven by any desired driving means,as an electric motor 45. A suitable fuel pump (not shown) may beprovided and driven from a worm gear' mechanism (indicated at 46). Theatomizing cup 41 is mounted on the inner end of the shaft 21 forrotation therewith, and is flared internally toward the open end.Extending longitudinally through the shaft 21, which is hollow for thispurpose, is an elongated A fuel nozzle 48 is mounted than the highpressure side,

I8 is t coaxially substantially through said secondary 'shaft rotatablysupporting said cup,

on the outlet end of the tube 49 within the atom izing cup 41. The otherend of the tube 49 is adapted to be connected through a valve mechanism50 to the source of fuel. The valve 50 is interconnected trolling thesup ly of fuel and secondary air.

I claim as my invention:

1. In an oil burner, the combination comprising a secondary air nozzlehaving the shape of a Venturi tube with an inlet cone, a throat and anexpanding outlet cone, a primary air nozzle Q extending through saidsecondary air nozzle in peripherally spaced relation thereto, saidprimary air nozzle being tapered toward its dissage of Venturi shape,means for supplying fuel oil axially through said primary air nozzle,and

means for supplying air under superatmospheric pressure to said primarynozzle and to said secondary nozzle.

2. In an oil burner, the combination comprising, a secondary air nozzleadapted to be supported on and to discharge through a furnace wall, saidnozzle having the shape of a Venturi tube with an inlet cone andanexpanding cone, 2. primary air nozzle extending into said secondary airnozzle, said primary air nozzle being tapered from the region of minimumlateral flow area of said secondary nozzle toward its discharge end toprovide with said secondary air nozzle an annular air passage of Venturishape, means for supplying air under superatmospheric pressure to saidprimary nozzle, means for supplying air under superatmospheric pressureto said secondary air nozzle, a fuel nozzle mounted coaxially of andextending into said primary air nozzle, and means for supplying fuel oilto said fuel nozzle.

2. In a fuel oil burner, in combination, a secondary air nozzle havingsubstantially the shape of a Venturi tube, a primary air nozzleextending into said secondary air nozzle and coacting with saidsecondary nozzle to define an inter- Vening annular air passage havingsubstantially a Venturi shape in cross section taken longitud'b nally ofsaid passage, a shaft extending axially of said nozzles, an atomizingcup on said shaft and extending into said primary air nozzle, a fuelsupply tube extending through said shaft, a fuel nozzle on said tube todischarge fuel oil within said cup, and means for supplying combustionair under forced draft to both of said air nozzles.

4. .In an oil burner, ing, a secondary air the combination comprisnozzlewith an inlet cone,

- an intermediate straight throat and an expanding outlet cone, 2.primary air nozzle extending nozzle andcoacting therewith to define anannular secondary air passage, said primary nozzle being tapered towardits discharge end within said outlet cone to expand the outer end ofsaid passage, a plurality of peripherally spaced helical vanes in saidoutlet cone inclined in one dimotion to impart a swirling motion to theair atomizing cup extending coaxially substantially through said primarynozzle and coacting therewith to define an annular primary air passagerestricted in the region of taper of said primary nozzle, a drive ofhelical vanes fixed in the tapered portion of said primary nozzle inperipherally spaced relawith the rod 25 for jointly con- 5 pointadiacent the minimum 15 I der forced draft to said air nozzles.

5. In an oil burner, the combination compris ing, a secondary air nozzlewith an expanding outlet cone, a primary air nozzle extending coaxiallysubstantially through said secondary nozzle and coacting therewith todefine an annular secondary air passage, said primary nozzle beingtapered toward its discharge end within said outlet cone, a plurality ofperipherally spaced vanes in said outlet cone, an atomizing cupextending coaxially substantially through said primary nozzle andcoacting therewith to define an annular primary air passage restrictedin the region of taper of said primary nozzle, a drive shaft rotatablysupporting said cup, a plurality of helical vanes fixed in the taperedportion of said primary nozzle in peripherally spaced relation aboutsaid cup, a fuel nozzle to discharge fuel oil in said cup, means forsupplying fuel to said fuel nozzle, and means for supplying air underforced draft to said air nozzles.

-6.' In a fuel oil burner, in combination, two spaced concentric airnozzles terminating'substantially in a common transverse plane anddefining an intervening annular air passage, the opposed walls of saidnozzles being relatively longitudinally inclined to each other to impartto said passage a shape flaring from a transverse plane of minimum flowarea intermediate the ends of said nozzles to the discharge end, anatomizing cup extending coaxially and in peripherally spaced .relationsubstantially through the inner nozzle and coacting therewith todefinean intervening annular air passage, the opposed walls of said innernozzle and said cup being relatively longitudinally inclined to. eachother to progressively restrict the flow area of the outer end portionof said last mentioned passage, means for rotating said cup, a fuelnozzle to discharge fuel oil in the inner end of said cup, means forsupplying fuel to said fuel nozzle,

and means for supplying air under forced draft to both of said airpassages.

7. In a fuel oil burner, in combination, a secondary air nozzle havingsubstantially the shape of a Venturi tube, a primary air nozzleextending into said secondary air nozzle and coacting with saidsecondary air nozzle to define an intervening annular air passage havinga shape flaring longitudinally to transverse plane of minimum flow areaintermediate the ends of said nozzles, a tubular shaft extending axiallyof said nozzles, an atomizing cup on said shaft and extending into saidprimary air nozzle and coacting with said primary air nozzle to definean intervening annular air passage, a fuel nozzle mounted in the innerend of said atomizing cup and connected to receive fuel axially throughsaid shaft and to discharge the fuel within said cup, and means forsupplying combustion air under forced draft to both of said nozzles.

f WILLIAM O. BEHRENS.

the discharge end from a

